Projecting attributes of function return values

Hi all

I have a simple patch about the treatment of functions.
But it may be self-satisfied.
Please check my patch at the end of this posting.

Case 1. executor evaluates functions twice

create table a (elem int4);
create function ax2(int4) returns a as
'select $1*2;' language 'sql';
select elem(ax2(1));

the result is

elem
----
4
(1 row)

it's wrong ?
it must be the following ?

elem
----
2
(1 row)

Case 2.parser rejects functions

create function elemout(a) returns int4 as
'select $1.elem;' language 'sql';
select elemout(ax2(1));

ERROR: Function 'elemout' has bad return type 315169

this elog() is necessary ?
In my patch I removed it and the result is

elemout
-------
2
(1 row)

Thanks

Hiroshi Inoue
Inoue(at)tpf(dot)co(dot)jp

*** backend/parser/parse_func.c.orig Thu Dec 3 18:25:31 1998
--- backend/parser/parse_func.c Thu Dec 3 18:39:18 1998
***************
*** 1352,1358 ****
newexpr->typeOid = funcnode->functype;
newexpr->opType = FUNC_EXPR;
newexpr->oper = (Node *) funcnode;
! newexpr->args = lcons(first_arg, NIL);

return (Node *) newexpr;
}
--- 1352,1358 ----
newexpr->typeOid = funcnode->functype;
newexpr->opType = FUNC_EXPR;
newexpr->oper = (Node *) funcnode;
! newexpr->args = expr->args;

return (Node *) newexpr;
}
***************
*** 1359,1366 ****

}

- elog(ERROR, "Function '%s' has bad return type %d",
- funcname, argtype);
break;
}
case T_Param:
--- 1359,1364 ----